Process for stabilizing vinylidene chloride resins

Abstract

A process for imparting heat and light stability to vinylidene chloride copolymer resins by adding thereto small amounts of Vitamin E, an alkyl ester of thiodipropionic acid having 12 to 18 carbon atoms in an alkyl group thereof and an alkali metal salt or an alkali earth metal salt of a phosphoric acid.

What is claimed is: 
     
       1. A process for stabilizing a vinylidene chloride containing resin which comprises adding to 100 parts by weight of a vinylidene chloride copolymer from about 0.0005 to about 0.2 parts by weight per 100 parts by weight of the vinylidene chloride copolymer of Vitamin E, from about 0.0005 to about 0.2 parts by weight per 100 parts by weight of the vinylidene chloride copolymer of an alkyl ester of thiodipropionic acid having 12 to 18 carbon atoms in the alkyl groups thereof, and from about 0.0005 to about 0.2 parts by weight per 100 parts by weight of the vinylidene chloride copolymer of a phosphate selected from the group consisting of an alkali metal salt or an alkali earth metal salt of a phosphoric acid. 
     
     
       2. The process according to claim 1 wherein the vinylidene chloride copolymer has polymerized therein from about 60 to about 95 percent by weight of vinylidene chloride and from about 40 to about 5 percent by weight of a compolymerizable unsaturated monomer. 
     
     
       3. The process according to claim 2 wherein the copolymerizable unsaturated monomer is vinyl chloride. 
     
     
       4. The process according to claim 1 wherein the Vitamin E is selected from the group consisting of alpha-, beta-, gamma- and delta-tocopherols and mixtures thereof. 
     
     
       5. The process according to claim 1 wherein the Vitamin E is racemic-alpha-tocopherol. 
     
     
       6. The process according to claim 1 wherein the alkyl ester of thiodipropionic acid is either dilauryl thiodipropionate or distearyl thiodipropionate. 
     
     
       7. The process according to claim 1 wherein the alkali metal salt or alkali earth metal salt of a phosphoric acid is selected from the group consisting of sodium pyrophosphate and sodium tripolyphosphate. 
     
     
       8. A process for stabilizing a vinylidene chloride containing resin which comprises adding to 100 parts by weight of a vinylidene chloride copolymer from about 0.001 to about 0.05 parts by weight per 100 parts by weight of the vinylidene chloride copolymer of Vitamin E, from about 0.001 to about 0.05 parts by weight per 100 parts by weight of the vinylidene chloride copolymer of an alkyl ester of thiodipropionic acid having 12 to 18 carbon atoms in the alkyl groups thereof, and from about 0.001 to about 0.05 parts by weight per 100 parts by weight of the vinylidene chloride copolymer of a phosphate selected from the group consisting of alkali metal salts and alkali earth metal salts of phosphoric acids. 
     
     
       9. A process for stabilizing a resin containing from about 60 to about 95 percent by weight of vinylidene chloride and from about 40 to about 5 percent by weight of vinyl chloride which comprises adding to 100 parts by weight of said resin from about 0.001 to about 0.05 parts by weight per 100 parts by weight of the resin of racemic-alpha-tocopherol, from about 0.001 to about 0.05 parts by weight per 100 parts by weight of the resin of dilauryl thiodipropionate and from about 0.001 to about 0.05 parts by weight per 100 parts by weight of the resin of sodium pyrophosphate. 
     
     
       10. The process according to claim 1 including a fourth stabilizer selected from the group consisting of acetyl tributyl citrate and epoxidized linseed oil.